Twinning and dynamic recrystallization in AZ31 magnesium alloy under medium-high strain rate

Abstract

The uniaxial compression tests were carried out on AZ31 magnesium alloy samples at 150°C and 300°C and strain rates of 0.3s^-1, 3s^-1 and 10s^-1. The microstructures at various deformation conditions were detected by optical microscopy (OM) and the electron back scatter diffraction (EBSD). Schmid factor (SF) was employed to analyze the initiation of deformation modes. The secondary derivative method was used to identify the critical strain for twinning and DRX. Twinning is activated in the early stage of deformation and induces DRX, causing grain refinement. The microstructure and SF results show that the number of twins increases with strain rate and decreases with temperature increasing. Extension twinning is the main deformation mode (beside basal slip).